a. Field of the Invention
The instant invention is directed toward assessing tissue contact for flexible tip devices which may be implemented for use with catheters, and methods of manufacturing and using the flexible tip devices for assessing tissue contact. In particular, the flexible tip devices of the present invention may comprise one or more piezoelectric sensors for assessing tissue contact for mapping, ablation or other procedures.
b. Background Art
Various devices (e.g., electrode sensors, thermal sensors, ablation electrodes, etc.) may be implemented in catheters inserted into the patient's body (e.g., the patient's heart) for use in a wide variety of medical procedures, such as “mapping” the interior of the heart, thermal “mapping,” and tissue ablation, to name only a few examples. It is often desirable to determine the level of tissue contact between the device being used and the tissue the device is being used on.
By way of illustration, sensor output is only meaningful for mapping procedures when the sensors are in sufficient contact with the tissue being mapped. “False” signals received when the sensor is not in good or sufficient contact with the tissue may result in inaccurate mapping of the tissue (e.g., the interior of a patient's heart).
By way of further illustration, it is desirable to control the level of contact to form ablative lesions. In particular, it is desirable to maintain a constant level of contact between the ablation electrode and the cardiac tissue in order to elevate tissue temperature to around 50° C. and form lesions in the cardiac tissue via coagulation necrosis. Such lesions change the electrical properties of the cardiac tissue and may lessen or eliminate undesirable atrial fibrillations when formed at specific locations in cardiac tissue. Insufficient contact during the ablation procedure may result in poor lesion formation and/or damage to surrounding tissue in the heart.
Tissue contact is not always readily determined using conventional fluoroscopy techniques. Instead, the physician determines tissue contact based on his/her experience maneuvering the catheter. Such experience only comes with time, and may be quickly lost if the physician does not use the catheter on a regular basis. When used inside the heart, the beating heart further complicates matters by making it difficult to assess and maintain sufficient contact with the tissue for a sufficient length of time. If contact with the tissue cannot be properly maintained, advantages of using the device may not be fully realized.